Just bought an Exmark Vantage in the fall and since then it has gone through 2 batteries. The first one was fairly new and second one was put in this spring and it was a Partsmaster so no cheapo battery. Today that one went to shizz and now I'm looking into a third batt within 1 month of mowing. This mower does have a small alternator in it so do you guys think there may be something wrong with electrical components or just some bad luck?